The cost of a two-year legal battle over a £36.50 cake is set to hit almost £180,000.

Senior judges yesterday threw out an appeal against a ruling that a family-owned bakery's refusal to make a cake endorsing same-sex marriage was discriminatory. Ashers declined to make the cake iced with the slogan "Support Gay Marriage" as it conflicted with the owners' Christian beliefs.

The McArthur family will decide on their next course of action in the coming days after losing their bid to overturn the landmark judgment that found them guilty of discrimination.

Three Court of Appeal judges found the company had discriminated against gay rights campaigner Gareth Lee on grounds of sexual orientation by refusing to make the cake two years ago.

Ashers general manager Daniel McArthur said he was "extremely disappointed" with yesterday's ruling, adding that the family would now take advice before deciding on any further legal action. A decision is expected by Friday.

However, DUP MLA Jim Wells, who described the judgment as "an awful decision", said he would be encouraging the McArthurs to take the issue as far as they can.

Last night it emerged the cost of the case is approaching £180,000.

The Equality Commission is asking for an estimated £88,000 following the appeal.

Legal sources said a similar amount is likely to have been spent on the challenge by the McArthurs, whose costs have been covered by the Christian Institute, bringing the total bill to around £176,000.

It could rise further still if the McArthurs decide to continue their challenge.

Speaking outside the Court of Appeal yesterday, Mr McArthur said that equality law in Northern Ireland would have to change if it meant people could be punished for politely refusing to support others' causes.

"But now we are being told we have to promote the message, even if it is against our conscience. What we refused to do was to be involved with promoting a political campaign to change marriage law in Northern Ireland."

Ashers, which has six shops in the greater Belfast area, was initially prosecuted for refusing to bake the cake promoting same-sex marriage which also featured two Sesame Street characters.

Mr Lee, a member of the LGBT group Queer Space, was supported by the Equality Commission in his case against the bakery. He spoke of his relief that the appeal had gone in his favour.

Mr Wells, meanwhile, told the Belfast Telegraph that the case must now be referred to the Supreme Court and, if that fails, the European Court of Human Rights.

"I urge the McArthurs not to give up and if they do decide to launch a further appeal, I think the people of Northern Ireland should rally round and fund that appeal," he said.

In their legal battle to overturn the ruling, the McArthur family won the support of Attorney General, John Larkin QC.

During the hearing in May, he argued in court that the McArthur family was entitled to constitutional protection for turning down a customer's order based on their personal religious beliefs. Reacting to the decision yesterday, a spokeswoman for Mr Larkin's office said it "was a very careful judgment" to which he is going to give "very careful consideration".

From initial order to a tussle in the courts... how the long-running dispute unfolded

May 9, 2014: Gareth Lee places an order at Ashers.

May 11: Mr Lee is informed the order cannot be completed and offered a full refund.